But since Netflix notoriously doesn't release ratings data, it's hard to know just how big of a hit it is. Thankfully we have an estimate from a startup called SymphonyAM, which tracks Netflix ratings and has been cited by the likes of NBC.

SymphonyAM tells Business Insider that in the first 16 days, 8.2 million people watched "Stranger Things," which puts it ahead of all Netflix's recent releases except "Fuller House" and the new "Orange Is the New Black" season. It ranks before "Daredevil," "Jessica Jones," "House of Cards," and "Narcos."

If you haven't seen "Stranger Things," it's a supernatural sci-fi thriller that draws heavily from '80s movies and TV. It's a nostalgia play, done to perfection.

It currently has a 94% Rotten Tomatoes critic rating, a 96% audience rating, and it has sent the internet abuzz since it was released in mid-July. Analysts from Pacific Crest even take it as evidence that Netflix's system for producing shows is working the way it's supposed to.

But it almost didn't happen. In fact, co-creator Matt Duffer told Rolling Stone that "Stranger Things" had been rejected 15 to 20 times by different networks before Netflix.